1. Field of the Invention
The present invention relates to a filter system for recovering from a suspension a refined liquid freed of solid matters, etc. and obtaining a concentrated suspension.
2. Prior Art
Cross-flow type filters are often used to obtain refined filtrates by filtering large amounts of liquid feeds containing a relatively small amount of suspended matters. Such cross-flow type filters have been designed to be continuously operable over an extended period without a build-up of filter cakes on the surface of a filter medium by making the rate of a liquid feed flowing parallel with that surface higher than the rate of a filtrate passing through that filter medium. Usually, a cylindrical filter medium has been used so as to achieve a uniform and high-rate flow of a liquid feed.
However, the cross-flow filter using such a cylindrical filter medium has posed problems that if the area of the filter medium is increased so as to obtain an increased filter capacity, on the one hand, then it is required to increase the diameter or length of the filter medium and supply a large amount of a liquid feed, and if it is intended to obtain an increased filter capacity without increasing or decreasing the flow rate or speed of a liquid feed, on the other hand, then it is required to use a number of filter media each having a small diameter, thus resulting in the structure being complicated and increased in size. Another problem has been that the feed pump used is required to be of high pressure and large capacity.